Andrew Strauss has apologised to former England team-mate Kevin Pietersen after an obscene comment about the batsman was accidentally broadcast during a television commentary stint.

Strauss declared himself "mortified" and "profusely sorry" after he was heard referring to Pietersen as a "c**t" in what he thought was an off-air conversation.

But while the exchange occurred during a break in Sky's coverage of the Lord's Bicentenary match between a Rest of the World XI and MCC, it was broadcast to overseas listeners on an audio feed.

Pietersen, who has a rocky personal history with Strauss due to the 'textgate' row two years ago, was batting for the RoW team while Strauss described the action with Nick Knight.

Pietersen was fined by the England and Wales Cricket Board for tweeting critical comments about Knight in May 2012, but it was Strauss whose views were inadvertently aired.

When he returned to the commentary box later in the match Strauss addressed the controversy, saying: "I apologise unreservedly, particularly to Kevin Pietersen. I am mortified and profusely sorry."

Sky Sports had earlier made their own apology, tweeting: "Earlier comments were made during a break of play which were heard overseas. We apologise for the language used."

Piers Morgan, a close friend of Pietersen and a champion of his cause on social media since he was sacked by the ECB in February, called for Strauss to lose his job if the comments were verified.

The broadcaster tweeted: "If Strauss story is true then he'll have to be fired, surely? Or is a commentator calling @KP24 a 'c**t' on air acceptable @SkyCricket?

"After all, Strauss himself axed KP from his England team for allegedly saying similar things about him that were't even broadcast."

Morgan's latter comments refer to a troubled past between the former team-mates.

In 2012 Pietersen was dropped after sending messages to friends in the touring South Africa side which he admitted were "provocative".

Those messages were reported to be highly critical of Strauss, though suggestions that they included advice on how to get the opener out have been denied by Pietersen.

After a dramatic draw with the Proteas at Headingley, Pietersen started a memorably tetchy press conference by declaring he would not wait for skipper Strauss, who was also due to speak.

Speaking after the incident, Pietersen said: "I apologise to Straussy and the team for the inappropriate remarks at the press conference and for the texts. I truly didn't mean to cause upset or tension. I need to rein myself in sometimes."

Strauss, who retired soon after, reflected on the issue in his autobiography, Driving Ambition.

He wrote: "For me, he had crossed the line. He seemed to be at best destabilising and at worst undermining our carefully cultivated team environment.

"I did...have issues with him criticising me to the opposition. That felt like talking out of school, not to mention giving the opposition a way to drive a wedge between Pietersen and myself and the team."

Strauss has been conciliatory about Pietersen in much of his commentary work since then but it seems he may simply have been concealing less savoury views.